I've been toying around with an infinite grid using shaders in OpenGL 4.5, following this tutorial See that the cube is sliced in half. If I move the camera down, the rest of the cube will slowly appear. Conversely, if I move the camera up, the cube eventually disappears completely.

This is the underside of the grid. I should be able to see the cube through the grid, but the grid behaves like a solid object.

Does anyone have any ideas of what I'm doing wrong? Should I be enabling something in the application? For reference, I currently have this enabled:

glEnable(GL_MULTISAMPLE);
glEnable(GL_DEPTH_TEST);
glEnable(GL_BLEND);
glBlendFunc(GL_SRC_ALPHA, GL_ONE_MINUS_SRC_ALPHA);

CodePudding user response：

Blending only works when the Depth Test is disabled or the objects are drawn from back to front. When the depth test is enabled (with its default function GL_LESS) closer objects win against more distant objects. Even if a fragment's alpha channel is 0, the fragment affects the depth buffer and the depth test. Thus, a more distant fragment is discarded if a closer, transparent fragment was previously drawn.
You only have one object with transparent fragments, the grid. To solve your problem, just draw the grid after the cube:

• enable depth test
• draw solid objects (cube)
• enable blending
• draw grid